Rapid prototyping covers a number of industrial techniques designed to produce a physical prototype in a minimum of time, starting from a 3D CAD design. Silicone is widely used as it permits rapid prototyping (only a few days) and is more economical than typical 3D moulds.
The object made by the rapid prototyping can be used for functional and ergonomic testing, with the certainty that actual conditions of use can be verified. The process involves a number of steps:
- CAD design of the object to be made;
- production of the "master" by stereolithography;
- Pouring the silicone around the "master" to create a mould;
- cutting the mould to extract the master;
- pouring resin inside the silicone mould to produce the prototype;
- functional and ergonomic tests on the prototype;
- approval of the prototype;
- industrialisation and mass production.
This type of technology is ideal for the pre-production phase as it reduces the risks of poor design and avoids significant economic damage.
For this application, Zhermack has developed a poly-addition RTV2 silicone with a mixing ratio of 10 parts A:1 part B (in weight) and a Shore A hardness of about 42.
XTX 45 - Part 10 Catalyst
XTX 45 DRY – Part 1 Base
XTX 45 OIL BLEEDING – Part 1 Base
Also available is a poly-addition RTV2 silicone with a Shore A hardness of 45, a mixing ratio of 1:1 (in weight) and very low viscosity, with mechanical characteristics specifically for prototyping small, detailed parts.
In the "oil bleeding" version, the mould is guaranteed to resist contact with particularly aggressive substances, such as polyurethane resins.
With this duplication technique, small series of objects can be produced with almost identical mechanical, aesthetic and dimensional characteristics to the finished product.
The following resins can be used to make the prototype:
- various hardnesses of rubber;
- resins that simulate common thermoplastics, such as polypropylene, ABS, polycarbonate, nylon, etc.;
- loaded resins.
To ensure correct use and obtain the characteristics of the final product, use the poly-addition silicones at a ratio of 10:1 and 1:1. The surface must be completely clean. Once the products have been poured, the components should be mixed vigorously until a homogeneous compound is obtained. A vacuum must be generated and the product poured from the recommended height of about 30 cm. Store the product at a temperature of between 5°/25°C and close the bottles tightly after use.